Question 854218
Doing this yourself, maybe with values other than I might use, would be much, much, much better than blindly using what I show here.


420 apples being only 35% of what the grandfather needs, if n is how much apples "needed", then this makes a proportion:

{{{420/n=35/100}}}
More conveniently used as
{{{n/420=100/35}}}
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You want to apply some factor, approximately {{{100/35}}}, to the 420, in order to estimate a better quantity of needed apples.  what easy and near factor is this?  You might have a feeling that {{{100/35}}} is about 3.  Maybe do {{{420*3}}} IN YOUR HEAD.